This document discusses mapping collision risk for the little bustard with power lines. It describes tracking 31 little bustards using satellite telemetry to collect over 75,000 locations over multiple years. This data was used to create maps showing collision risk during daily movements and migration for breeding, post-breeding, and winter periods. Collision risk was calculated based on population density, distance traveled, and percentage of flights at risk heights near power lines. The maps can help identify hazardous power line sites and inform planning of new power lines.

1. Mapping the risk of collision of Little Bustard’s with
power lines: implications for the planning of new
power lines and identification of existing power lines
at hazardous sites
João Paulo Silva
Centre for Applied Ecology “Prof. Baeta Neves”, Institute of Agronomy, Technical University of Lisbon, Portugal;
Agronomy, Lisbon,
Foto: Luís Venâncio
Centre for Environmental Biology, Faculty of Science, University of Lisbon, Portugal;
Biology, Science, Lisbon, Portugal;
u

2. Background
• The little bustard is a leking grassland bird
gg g
• Males establish territories in a aggregated
manner and attract females
• Parental care is provided singly by the
female
• Are gregarious during the rest of the year
• During the yearly cycle this species
performs movements towards areas with
greater food availability, depending on
different areas along the yearly cycle

3. Interactions with power lines
• Considered to be one of the most susceptible species to
collision with overhead distribution power lines
• A rough estimate shows that impacts caused by overhead
power lines are lightly to be significant:
• Estimates that overhead power lines cause
mortality to at l
li least 1 5% of the population yearly
1.5% f h l i l
• Highly susceptible to suffer accidents because:
• Gregarious
• Migrate during night
g g g
• Habitat with a high density of power lines
• Vision not optimized to look ahead

4. Usefulness of mapping collision risk
• Mitigation measures used to prevent
collision of birds are mostly related to
the marking of the conductors and
earth cable
• However these measures have
shown not to be very effective,
usually with an efficiency estimated
y y
under 60%
• It is acknowledged that the most
efficient action to prevent collisions
ffi i t ti t t lli i
with power lines is through planning
Need for collision risk maps mainly for structuring power lines
maps,

5. Mapping collision risk - Methods
2 types of collision risk maps:
– Collision risk maps within each season (
p (breeding, p
g, post-
breeding and winter):
• Daily movements at 2 hour-intervals measured from
satellite telemetry
• Focal observations used to:
– C lib t th estimates of 2 h
Calibrate the ti t f hour i t
interval
l
movements derived from satellite telemetry
– Describe the frequency of different types of flights
that were recorded at different heights
– Collision risk map for the migratory movements, usually
between seasons
• U i d t f
Using data from th satellite t ki
the t llit tracking

6. Mapping collision risk - Methods
Satellite telemetry –
study area
• Captures conducted at 2
priority conservation sites:
– Castro Verde – more than
half of the breeding
population within SPAs
and approximately 20% of
the national population
– Vila Fernando – priority
site for breeding with high
density of breeding males
d it f b di l

7. Mapping collision risk - Methods
Satellite telemetry
Satellite tracking
• Took place between April 2009 and August 2011
• For most birds that died we were able recover the PTT
Captures
• Prevent capture miopathy - need to manipulate the birds in
less than 30 min
• Previous training of the team

8. Mapping collision risk - Methods
Satellite telemetry
• Study of the movements of the Little Bustard using satellite
telemetry:
– Microwave solar PTT/GPS 30 gr
– Programmed to obtain a fix every 2 hours (maximum
number of fixes possible)
– During winter and part of autumn and spring the number of
night fixes was reduced to manage the battery

9. Mapping collision risk - Methods
Focal observations
• Field work took place at the sites were the birds were tracked
– Alentejo, Extremadura and Castilla y Leon
j ,
• Conducted for a maximum of 2 hour periods
– How far it flew
– Time in flight
– Mean flight height, in one the following categories:

10. > 30 meters
Focal observations
15 – 30 meters
1 – 15 meters

11. Mapping collision risk - Methods
Map building process
∫( )
Collision risk during
C Distance
1
Population % flights at
daily movements ~ density + travelled in + risk height
flight
total daily flight distance at risk height within 1 Km2
Collision risk during
2
migration movements
density of migratory flights within a 2,5 x 2,5 Km grid

12. Mapping collision risk - Methods
Collision risk daily movements
∫( )
Collision risk during Population Distance % flights at
daily movements ~ density + travelled in + risk height
flight
• Population density (based on the data collected in a previous
Life project – Life Sisão)
– Modelling little bustard’s presences using Maxent, using
the following variables
• Regional autocorrelation
• LandCoverCorine 2006
• Soil productivity
– Adapted probabilities into a approximate population
density map

13. Mapping collision risk - Methods
Collision risk daily movements
∫( )
Collision risk during Population Distance % flights at
daily movements ~ density + travelled in + risk height
flight
• Distance travelled in flight
– All migratory movements removed from the data set
– Distance between locations given every 2 hours with GPS
p
precision (
(error aprox. 18m)
p )

14. Mapping collision risk - Methods
Collision risk daily movements
∫( )
Collision risk during Population Distance % flights at
daily movements ~ density + travelled in + risk height
flight
• % of flights at risk height
– Calculated as an average of the flight heights

15. Mapping collision risk - Results
• Overall 31 birds were captured
and fitted a PTT
– 8 in Vila Fernando
– 23 i C t V d
in Castro Verde
• 27 of which transmitted
between one month and 2 and
half years
• Over 75.000 location were
collected, summing
approximately 21.500 Km of
movements as given by the
satellite tracking

16. Mapping collision risk - Results
∫( )
Collision risk during Population Distance % flights at
daily movements ~ density + travelled in + risk height
g
flight
Breeding Post-breeding Winter
Max. – 19.4 birds/Km2 Max. – 8.6 birds/Km2 Max. – 14.4 birds/Km2

17. Mapping collision risk - Results
∫( )
Collision risk during Population Distance % flights at
daily movements ~ density + travelled in + risk height
g
flight
Breeding Post-breeding
Daily distance travelled: 3028m Daily distance travelled: 9311m

18. Mapping collision risk - Results
∫( )
Collision risk during Population Distance % flights at
daily movements ~ density + travelled in + risk height
g
flight
Winter
Daily distance travelled: 10 873m
10.873m

19. Mapping collision risk - Results
∫( )
Collision risk during Population Distance % flights at
daily movements ~ density + travelled in + risk height
g
flight
Mean flight altitude
100
90
80
70
60
1-15
50
15-30
40
>30
30
20
10
0
Primavera Verão Inverno
Mean frequency of flight height per season (%)
Breeding Post‐breeding Winter
g g
15‐30 7 23 14

20. Mapping collision risk - Results
∫( )
Collision risk during Population Distance % flights at
daily movements ~ density + travelled in + height risk
g
flight
Breeding Post-breeding Winter

21. Mapping collision risk - Results
∫( )
Collision risk during Population Distance % flights at
daily movements ~ density + travelled in + height risk
g
flight
Annual collision risk
based on daily
movements

22. Mapping collision risk - Results
Distribution of
Di t ib ti f
medium and high
tension power lines
p
crossing areas of
greater collision risk

23. Mapping collision risk - Results
Collision risk during migration movements
(m)

24. Mapping collision risk - Results
Collision risk during migration movements

25. Mapping collision risk - Results
Collision risk during migration movements

26. Mapping collision risk - Results
Collision risk during migration movements
Castro Verde Vila Fernando

27. Mapping collision risk - Results
Collision risk during migration movements
Migration movements

28. Mapping collision risk - Results
Collision risk during migration movements

29. Mapping collision risk - Results
Collision risk during migration movements

30. Mapping collision risk - conclusions
• Collision risk maps for daily movements and migration
movements are now available and can be used in the planning
of new power lines and apply mitigation measures for existing
ones
• During the breeding season the collision risk is low due to low
frequency of flights at height risk and short flight distances
• The winter season has the highest collision risk, because of
the co-occurrence of larger areas with higher population
density and longer distances flown during that season
• No particular migration corridors were used, however regions
with higher density of migratory movements in the studied
populations were identified

31. Acknowledgements